Extended Outlook: After Next Week, Rest of May Cooler

Posted May 14, 2009, 7:16 PM.

After a warmer than normal first half of May, longer term weather models indicate that conditions, especially temperatures, will snap back to seasonal norms after Wednesday or so next week.

Dry weather is still predicted; we may exit the month without any measurable rain in the inland valleys.

Temperatures should be warm or even very warm this weekend, ranging from the middle 80's in Fallbrook and De Luz to the upper 80's in southwest Riverside County, to the middle 90's and above in the inland valleys north of Elsinore convergence zone, including Lake Elsinore, the Riverside metro, Perris, Sun City and the San Jacinto Valley.

By the middle of next week, temperatures are projected to settle back to normal, and, according to NOAA's CPC outlook and the GFS model, should remain in the normal range for the rest of the month.

For most of the inland valleys, that likely means a return to onshore flow and morning low clouds, seasonal climate features nicknamed "May Gray" that have been sporadic in the first half of this month.

It isn't unusual for May to be dry, but there have been some wet Mays in the past decade, including 2008 and 2003. Last year's rainfall was from thunderstorm activity that also spawned tornadoes in Moreno Valley and Perris. 2005 and 2006 also experienced moderate rainfall.

May rainfall in the inland valleys, on average, runs about a quarter to a third of the rainfall typically received in April.

Afternoon temperatures have been running near to slightly above normal for the last several days.